Articles prepared by using polymers such as polyethylene, polypropylene and polybutylene have advantages over articles prepared by using glass, metal and wood, as they are lighter in weight, rust free, easily moldable and reusable. However, creep rupture (slow crack growth) and environmental stress cracking in the polymers result in brittle breaks and macroscopic cracks in the articles without any visible warning.
Several attempts were made in the past to reduce creep rupture and improve the environmental stress crack resistant properties of polymers by tailoring molecular weight, molecular weight distribution (Mw/Mn) and melt processability of polymers. It is observed that the mixing of ultra-high molecular weight polyethylene with relatively low molecular weight polymer improves environmental stress crack resistant property of the resultant polymer composition.
For instance, WO1994028064 discloses polyethylene compositions comprising polyethylene and ultrahigh molecular weight polyethylene (0.1 to 40%). Ultrahigh molecular weight polyethylene (UHMWPE) used in accordance with WO1994028064 is characterized by molecular weight greater than 1.5×106, meting point of about 133.5° C. and bulk density of about 0.93 g/cm3. These characteristics of UHMWPE indicate that the WO1994028064 employs regular ultrahigh molecular weight polyethylene (Regular UHMWPE).
Further, CN102167860 discloses a process for preparing a self-reinforced polyethylene blend. The process involves use of xylene to dissolve 1 to 3 parts of ultrahigh molecular weight polyethylene (UHMWPE) with 100 parts of high-density polyethylene (HDPE). A homogenous solution of UHMWPE and HDPE so obtained is then precipitated and dried to obtain UHMWPE/HDPE precipitate.
Still further, US20120004358 discloses compositions comprising intimate blends of ultrahigh molecular weight polyethylene and high-density polyethylene (HDPE). The amount of UHMWPE in the blend is in the range of 50 to 90%.
Known prior art prefer polymer compositions containing regular ultrahigh molecular weight polyethylene (Regular UHMWPE) and high density polyethylene. However, such compositions are associated with drawbacks such as the use of high amounts of regular UHMWPE. Secondly, the use of regular UHMWPE leads to non-homogeneous mixing of regular UHMWPE in the polyethylene matrix.
Accordingly, there is a need for a polymer composition having homogenous dispersion of polymers. Further there is also need for a polymer composition having better physical properties such as creep resistance, environmental stress crack resistance, stress bearing capability, stiffness and ductility.